Factor analysis of chemical ionization experiments: Numerical simulations and an experimental case study of the ozonolysis of α-pinene using a PTR-ToF-MS
Factor analysis of chemical ionization experiments: Numerical simulations and an experimental case study of the ozonolysis of α-pinene using a PTR-ToF-MS
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化学电离实验的因素分析：使用 PTR-ToF-MS 进行 α-蒎烯臭氧分解的数值模拟和实验案例研究
DOI：
10.1016/j.atmosenv.2018.11.012
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发表时间：
2019
影响因子：
5
通讯作者：
M. Bilde
中科院分区：
文献类型：
--
作者：
B. Rosati;R. Teiwes;K. Kristensen;R. Bossi;H. Skov;M. Glasius;Henrik B Pedersen;M. Bilde
在这项研究中，我们研究了应用因子分析技术的化学电离仪器质子转移反应飞行时间质谱仪（PTR-ToF-MS）记录的数据集。进行了数值模拟，以测试和优化的因子分解方法多元曲线分辨率-交替最小二乘（MCR-ALS）的性能。模拟结果表明，因子分析初始估计的选择对因子分解的结果至关重要。为此，我们描述了一种新的方法的基础上的皮尔逊相关系数，与其他测试方法相比，产生最好的因式分解结果。不同物质对某一质量箱的重叠贡献和数据中的大不确定性使因子分析的性能恶化。反卷积技术也被应用到在烟雾室采用PTR-ToF-MS获得的数据。从单一物质（裂解模式），如α-蒎烯，α-蒎烯氧化物和蒎醛，以及一个更复杂的实验，涉及臭氧分解的α-蒎烯的响应进行了研究。对于单一物质，因子分解法指出存在杂质，这些杂质可以与实际物质的质量相区分。用因子分解技术对α-蒎烯臭氧化反应进行了分析，得到了4个因子，其中1个因子代表反应物的衰变，3个因子代表不同的产物。矩阵分解技术似乎是一个有价值的工具，允许详细分析复杂的质谱，而不需要任何先验信息。
In this study we examine the application of a factor analysis technique for datasets recorded by the chemical ionization instrument Proton Transfer Reaction - Time-of-Flight - Mass Spectrometer (PTR-ToF-MS). Numerical simulations were carried out to test and optimize the performance of the factorization method Multivariate Curve Resolution - Alternating Least Squares (MCR-ALS). The simulations demonstrated that the choice of initial estimates for the factor analysis are crucial for the outcome of the factorization. For this purpose we describe a new method based on the Pearson correlation coefficient which, compared to the other tested methods, yields the best factorization results. Overlapping contributions of different substances to a certain mass bin and large uncertainties in the data deteriorate the performance of the factor analysis. The deconvolution technique was also applied to data obtained with a PTR-ToF-MS employed at a smog chamber. The response from single substances (fragmentation patterns) such as α-pinene, α-pinene oxide and pinonaldehyde as well as a more complex experiment involving the ozonolysis of α-pinene are investigated. For the single substances, the factorization method points to the presence of impurities which could be differentiated from the masses affiliated with the actual substances. The α-pinene ozonolysis experiment was analysed with the factorization technique and yielded four factors, one representing the decay of the reactant and three different products. The matrix factorization technique appeared to be a valuable tool allowing for a detailed analysis of complex mass spectra without the need of any prior information.